Fluid pump assembly

ABSTRACT

A fluid pump assembly includes a double acting fluid cylinder with a housing, a piston reciprocally disposed within the housing, and a piston rod carrying the piston and extending from the housing. The piston rod has an end. A pump includes a pump body, a pressure loaded seal and a wiper seal. The pump body has a fluid inlet, a pump chamber and a rod port. The inlet is configured for receiving a fluid to be pumped and is in fluid communication with the pump chamber. The piston rod extends through the rod port and the end is positioned within the pump chamber. The pressure loaded seal is positioned within the rod port around the piston rod and has a pressure loaded end face toward the pump chamber. The wiper seal is positioned within the rod port around the piston rod on a side of the pressure loaded seal opposite from the pump chamber. The pump body further has a scavenging groove in an area between the pressure loaded seal and the wiper seal. The scavenging groove is in fluid communication with the inlet, whereby any fluid which leaks past the pressure loaded seal is returned to the inlet.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation-in-part of U.S. patent application Ser. No. 12/433,914, entitled “FLUID PUMP ASSEMBLY”, filed May 1, 2009, which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to fluid pumps, and, more particularly, to reciprocating piston type fluid pumps.

2. Description of the Related Art

Fluid pumps are utilized for various purposes. One such use is to pump an epoxy into a crack in concrete, such as in a wall or floor of a building. The epoxy typically is a two-part epoxy with a catalyst and a base. The catalyst is kept in one supply hopper and the base is kept in another supply hopper. Separate pumps are usually used to separately pump the catalyst and base to a mixing unit immediately before application within the crack(s). An example of a pump arrangement used to pump an epoxy is disclosed in U.S. Pat. No. 4,828,148, also invented by the inventor of the present invention.

A problem with known pump arrangements of the type described above is that they tend to be relatively large, complex and expensive. Another problem is that the pumped fluid can sometimes leak past the seals within the pump. The pumped fluid, such as a two part epoxy, can then be discharged into the ambient environment. In the case of an epoxy, this can cause personnel slippage problems, increases material costs, can set up and harden in undesirable locations, and can cause undesirable odors.

What is needed in the art is a fluid pump which can accommodate fluids of different viscosities, simple to assemble, clean and operate, economical, and handles any leaking fluid in a better manner.

SUMMARY OF THE INVENTION

The present invention provides a fluid pump with a reciprocating piston which is sealed within the pump body using a pressure loaded seal (e.g., chevron seal) and a wiper seal positioned on a side of the chevron seal opposite the pump chamber. A fluid scavenging arrangement is positioned between the pressure loaded seal and wiper seal for recycling any fluid which leaks past the pressure loaded seal back to an inlet of the pump.

The invention in one form is directed to a fluid pump assembly including a double acting fluid cylinder with a housing, a piston reciprocally disposed within the housing, and a piston rod carrying the piston and extending from the housing. The piston rod has an end. A pump includes a pump body, a pressure loaded seal and a wiper seal. The pump body has a fluid inlet, a pump chamber and a rod port. The inlet is configured for receiving a fluid to be pumped and is in fluid communication with the pump chamber. The piston rod extends through the rod port and the end positioned within the pump chamber. The pressure loaded seal is positioned within the rod port around the piston rod and has a pressure loaded end face toward the pump chamber. The wiper seal is positioned within the rod port around the piston rod on a side of the pressure loaded seal opposite from the pump chamber. The pump body further has a scavenging groove in an area between the pressure loaded seal and the wiper seal. The scavenging groove is in fluid communication with the inlet, whereby any fluid which leaks past the pressure loaded seal is returned to the inlet.

The invention in another form is directed to a fluid pump assembly including a double acting fluid cylinder including a housing, a piston reciprocally disposed within the housing, and a piston rod carrying the piston and extending from opposite ends of the housing. The piston rod has a first end and a second end. A first pump includes a pump body, a fluid inlet, a pressure loaded seal and a wiper seal. The pump body has a pump chamber and a rod port. The piston rod extends through the rod port and the first end positioned within the pump chamber. The pressure loaded seal is positioned within the rod port around the piston rod and has a pressure loaded end face toward the pump chamber. The wiper seal is positioned within the rod port around the piston rod on a side of the pressure loaded seal opposite from the pump chamber. A second pump includes a pump body, a fluid inlet, a pressure loaded seal and a wiper seal. The pump body has a pump chamber and a rod port. The piston rod extends through the rod port and the second end is positioned within the pump chamber. The pressure loaded seal is positioned within the rod port around the piston rod and has a pressure loaded end face toward the pump chamber. The wiper seal is positioned within the rod port around the piston rod on a side of the pressure loaded seal opposite from the pump chamber. The first pump and/or second pump include a fluid scavenging arrangement. The fluid scavenging arrangement has a scavenging groove in an area between a corresponding pressure loaded seal and wiper seal. The fluid scavenging groove is in fluid communication with a corresponding fluid inlet, whereby any fluid which leaks past the pressure loaded seal is returned to the corresponding inlet.

An advantage of the present invention is that fluid which leaks past the pressure loaded seal is returned to the fluid inlet of the pump, thereby reducing spillage into the work area and reducing raw material cost.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a perspective, partially exploded view of an embodiment of a fluid pump assembly of the present invention;

FIG. 2 is a side, partially sectioned view of the fluid pump assembly shown in FIG. 1;

FIG. 3 is a side sectional view of a pump, taken along line 3-3 in FIG. 2;

FIG. 4 is a sectional view illustrating in more detail the piston check;

FIG. 5 is a sectional view of the pressure loaded seal, taken along line 5-5 in FIG. 3;

FIG. 6 is a sectional view of the wiper seal, also taken along line 5-5 in FIG. 3;

FIG. 7 is a side, partially sectioned view of another embodiment of a fluid pump assembly of the present invention;

FIG. 8 is a side, partially sectioned view of yet another embodiment of a fluid pump of the present invention; and

FIG. 9 is a detailed view of a portion of the fluid pump shown in FIG. 8, taken at detail A, with the seal assembly installed.

Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates one embodiment of the invention, in one form, and such exemplification is not to be construed as limiting the scope of the invention in any manner.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, and more particularly to FIGS. 1 and 2, there is shown an embodiment of a fluid pump assembly 10 of the present invention which generally includes a double acting fluid cylinder 12, a first pump 14, and a second pump 16. In the embodiment shown, fluid pump assembly 10 is used for pumping one component of a two part epoxy from a hopper 18. However, it is to be understood that fluid pump assembly 10 can be used for pumping other types of fluids, depending upon the application. Hopper 18 is in fluid communication with each of first pump 14 and second pump 16 via a suitable fluid line 20.

Fluid cylinder 12 is configured as a double acting pneumatic cylinder in the embodiment shown, but could also be configured as a hydraulic cylinder, depending on the application. Fluid cylinder 12 generally includes a housing 22, piston 24, and piston rod 26. Housing 22 includes a pair of end caps 28 mounted to opposite ends of a cylinder 30. End caps 28 and cylinder 30 are constructed from a metal in the illustrated embodiment, but could also be constructed from a different type of material, such as a composite material. Piston 24 is reciprocally disposed within housing 22. Piston rod 26 carries piston 24 and extends through opposite ends 32 of housing 22 defined by end caps 28. Piston rod 26 has a first end 34 associated with first pump 14 and a second end 36 associated with second pump 16, as will be described in greater detail below.

In a preferred embodiment, each of first pump 14 and second pump 16 are directly mounted to respective end caps 28 to avoid alignment and deflection problems as piston rod 26 reciprocates during operation. First pump 14 and second pump 16 are configured substantially identical to each other in the illustrated embodiment. Accordingly, only first pump 14 will be described in detail herein, with it being understood that second pump 16 is substantially the same.

First pump 14 generally includes a pump body 38, a pressure loaded seal 40, a wiper seal 42, and a piston check 44. Pump body 38 defines a pump chamber 46, a rod port 48, a piston check port 50, an inlet 52, and an outlet 54. Piston rod 26 extends through rod port 48 and first end 34 of piston rod 26 reciprocates within pump chamber 46. Piston rod 26 is sealed within rod port 48 using pressure loaded seal 40 and wiper seal 42, as will be described in greater detail below.

Piston check 44 is mounted within piston check port 50 and functions to selectively fluidly interconnect inlet 52 with pump chamber 46 during operation. Conventional piston pumps typically use a ball check allowing one way flow of the fluid through the inlet to the pump chamber. However, a ball check can be strongly influenced by the viscosity of the fluid flowing through the inlet. A thicker fluid tends to quickly close the ball check while a thinner fluid may allow an appreciable amount of the fluid to flow past the ball prior to being seated. Piston check 44 is controlled using a cylindroid valve or other suitable actuator to positively open and close the flow path between inlet 52 and pump chamber 46. Piston check 44 is sealed within piston check point 50 using suitable seals carried by seal holders 56.

Pressure loaded seal 40 and wiper seal 42 together function to effectively seal pump chamber 46 during a compression stroke of piston rod 26. Pressure loaded seal 40 and wiper seal 42 also function together to effectively wipe any of the fluid from the outside periphery of piston rod 26 during a return stroke of piston rod 26.

As used herein, a “pressure loaded seal” or “high pressure seal” is intended to mean an annular seal with an axial end face which expands to seal between a rod and surrounding body. For example, a pressure loaded seal may have an axial end face which is generally U-shaped or V-shaped in cross section. Fluid under pressure adjacent the end face causes the seal to expand radially, thereby providing an effective seal. One such seal, known in the industry as a “chevron seal”, and shown in the embodiment illustrated in FIGS. 3 and 5, has a generally V-shaped cross section (the entire seal is generally V-shaped in cross section, rather than just the end face). A spring arrangement may be employed within the V-shaped cavity on the open face of the chevron seal to further assist in providing effective sealing.

Referring to FIGS. 3 and 5, conjunctively, pressure loaded seal 40 is positioned within rod port 48 around piston rod 26 and has a pressure loaded end face 60 which faces toward pump chamber 46. Pressure loaded seal 40 is configured as a “chevron” seal in the illustrated embodiment, and thus is generally V-shaped in cross section. It is also possible to use a pressure loaded seal with a different shape, such as a seal with a U-shaped cross section or a pressure loaded end face with a U-shaped cross section.

Wiper seal 42 is positioned within rod port 48 around piston rod 26 on a side of pressure loaded seal 40 which is opposite from pump chamber 46 (i.e., closest to fluid cylinder 12). Wiper seal 42 has an annular lip 62 which functions to wipe fluid (e.g., epoxy component) from the outer periphery of piston rod 26 during a return stroke.

With a conventional wiper seal, lip 62 is usually oriented toward the outside of the pump body and simply acts to prevent foreign matter from entering the annular area around piston rod 26 and contaminating the interior of pump 14. However, with the present invention, the orientation of wiper seal 42 is reversed such that lip 62 is at the axial end of wiper seal 42 which is closest to pump chamber 46. This allows the epoxy component or other fluid to be effectively wiped from the outer periphery of piston rod 26.

Pressure loaded seal 40 and wiper seal 42 can be respectively carried within annular recesses which are directly formed in rod port 48. However, for manufacturing purposes, a seal holder 64 forming part of housing 22 can be formed with the internal recesses for holding pressure loaded seal 40 and wiper seal 42.

During a return stroke of piston rod 26, first end 34 is drawn toward fluid cylinder 12 and piston check 44 is open to allow the epoxy component to flow into pump chamber 46. During the return stroke, there is no pressure within pump chamber 46 and, in fact, may be a slight vacuum pressure to assist in pulling the epoxy component into pump chamber 46. Without pressure within pump 46, pressure loaded seal 40 does not radially expand to prevent the epoxy component from flowing therepast toward wiper seal 42. Lip 62 of wiper seal 42 effectively wipes the epoxy component from the outer periphery of piston rod 26 and the epoxy component returns past the relaxed chevron seal 40 to pump chamber 46.

During a compression stroke within first pump 14, first end 34 of piston rod 26 moves away from fluid cylinder 12 and the pressurized epoxy component is pumped from outlet 54. Piston check 44 is closed during the compression stroke to prevent the epoxy component from flowing back out inlet 52.

When fluid pump assembly 10 is configured with both a first pump 14 and a second pump 16 as illustrated, first pump 14 pumps the epoxy component through outlet 54 while second pump 16 draws the epoxy component through inlet 52, and vice versa. This provides a continuous flow of the epoxy component to other downstream devices, such as a mixing device for mixing the two epoxy components together. To this end, each piston check 44 is selectively actuated such that when one piston check is open, the other piston check is closed. During a compression stroke, the piston check is closed to force the epoxy component from the corresponding outlet, and during a return stroke the piston check is open to draw the epoxy component into pump chamber 46.

FIG. 7 is a side, partially sectioned view of another embodiment of a fluid pump assembly 70 of the present invention. In contrast with fluid pump assembly 10 described above, fluid pump assembly 70 includes a pair of pressure loaded seals 72 and 74, and a pair of wiper seals 76 and 78. Pressure loaded seals 72 and 74 are each configured as U-cup seals in the illustrated embodiment, but could be differently configured, such as a chevron seal, etc. Pressure loaded seal 72 and wiper seal 76 are each carried by a seal holder 80 associated with pump 82, and wiper seal 78 is carried by a seal holder 84 at the interface between pump 82 and air cylinder housing 86. The annular space 88 between seals 72 and 76, as well as the annular space 90 radially outside of seal holder 80, can optionally be in fluid communication with each other and with the ambient environment to bleed any fluid which might flow past seal 72 to the ambient environment or other suitable location.

Referring now to FIGS. 8 and 9, there is shown a side, partially sectioned view of yet another embodiment of a fluid pump 100 of the present invention. Fluid pump 100 is preferably configured as part of a fluid pump assembly such as fluid pump assembly 10 shown in FIG. 1. For simplicity sake, only a single fluid pump 100 is shown in FIGS. 8 and 9, with it being understood that when configured as a dual pump arrangement, an identically configured fluid pump 100 is also connected to a fluid cylinder, such as fluid cylinder 12 shown in FIG. 1. Fluid pump 100 is similar in many respects to the other fluid pumps shown in FIGS. 1-7. For example, fluid pump 100 includes a fluid inlet 102, pump chamber 104, pressure loaded (or high pressure) seal 106, and wiper (or low pressure) seal 108 (cf. references 52, 46, 40 and 42 in FIGS. 3 and 4). Moreover, fluid pump 100 includes a fluid scavenging arrangement 110 which directs any fluid which might flow past high pressure seal 106 to fluid inlet 102 for reuse by the pump. Fluid scavenging arrangement 110 includes a scavenging groove 112 in the form of an annular groove which is in fluid communication with fluid inlet 102, whereby any fluid which leaks past pressure loaded seal 106 is returned to inlet 102.

It should be noted that the fluid pump arrangement shown in FIG. 8 also has an annular space 90 for directing any fluid which might flow past pressure loaded seal 72 to a suitable location, such as the ambient environment. Fluid scavenging arrangement 110 advantageously recycles any fluid which leaks past high pressure seal 106 back to the inlet of pump 110 so that the fluid can be reused. This avoids wasting the leaking fluid to the ambient environment, and reduces material costs.

With all piston pumps, leakage at the rod entry is inevitable. The pumps are then taken out of service not due to the insignificant loss of efficiency at the time, but rather leakage which may render an area unsafe due to slippage, odors, etc. Fluid scavenging arrangement 110 anticipates the failure (sooner or later) of both fluid seals 106 and 108. This allows the dispensing fluid pressure to impose on the air cylinder seals within fluid cylinder 12. The air cylinder seal would fail as the dispensing fluid pressures reach 1,000 psi or greater.

In order to manage such an event, fluid scavenging arrangement 110 includes the scavenging scavenge groove 112 aft of the two fluid seals 106 and 108 (i.e., scavenging groove 112 is located on a side of wiper seal 108 opposite from pressure loaded seal 106). Alternatively, and for certain applications, fluid scavenging groove 112 can be located between the two fluid seals 106 and 108. Pressure that builds in this area is vented back into the hopper of fluid inlet 102 which is gravity fed. Fluid scavenging arrangement 110 allows the pump to continues to operate indefinitely as the leakage is simply recycled internally. The pump is able to continue to operate in this fashion, but the loss of efficiency would be noticeable to an operator, signaling a need to replace fluid seals. In the meantime, the other fluid pump of the fluid pump assembly continues without disruption. There is no need to remove the unit until the loss of efficiency is unacceptable. This may be months beyond the initial seepage across the seals.

While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims. 

1. A fluid pump assembly, comprising: a double acting fluid cylinder including a housing, a piston reciprocally disposed within said housing, and a piston rod carrying said piston and extending from said housing, said piston rod having an end; and a pump including a pump body, a pressure loaded seal and a wiper seal, said pump body having a fluid inlet, a pump chamber and a rod port, said inlet being configured for receiving a fluid to be pumped and being in fluid communication with said pump chamber, said piston rod extending through said rod port and said end positioned within said pump chamber, said pressure loaded seal positioned within said rod port around said piston rod and having a pressure loaded end face toward said pump chamber, said wiper seal positioned within said rod port around said piston rod on a side of said pressure loaded seal opposite from said pump chamber, said pump body further having a scavenging groove in an area associated with said pressure loaded seal and said wiper seal, said scavenging groove being in fluid communication with said inlet, whereby any fluid which leaks past said pressure loaded seal is returned to said inlet.
 2. The fluid pump assembly of claim 1, wherein said scavenging groove is an annular groove surrounding said piston rod.
 3. The fluid pump assembly of claim 2, wherein said scavenging groove is located on a side of said wiper seal opposite from said pressure loaded seal.
 4. The fluid pump assembly of claim 1, wherein said fluid cylinder is an air cylinder.
 5. A fluid pump assembly, comprising: a double acting fluid cylinder including a housing, a piston reciprocally disposed within said housing, and a piston rod carrying said piston and extending from opposite ends of said housing, said piston rod having a first end and a second end; a first pump including a pump body, a fluid inlet, a pressure loaded seal and a wiper seal, said pump body having a pump chamber and a rod port, said piston rod extending through said rod port and said first end positioned within said pump chamber, said pressure loaded seal positioned within said rod port around said piston rod and having a pressure loaded end face toward said pump chamber, said wiper seal positioned within said rod port around said piston rod on a side of said pressure loaded seal opposite from said pump chamber; and a second pump including a pump body, a fluid inlet, a pressure loaded seal and a wiper seal, said pump body having a pump chamber and a rod port, said piston rod extending through said rod port and said second end positioned within said pump chamber, said pressure loaded seal positioned within said rod port around said piston rod and having a pressure loaded end face toward said pump chamber, said wiper seal positioned within said rod port around said piston rod on a side of said pressure loaded seal opposite from said pump chamber; wherein at least one of said first pump and said second pump include a fluid scavenging arrangement, said fluid scavenging arrangement having a scavenging groove in an area associated with a corresponding said pressure loaded seal and said wiper seal, said scavenging groove being in fluid communication with a corresponding fluid inlet, whereby any fluid which leaks past said pressure loaded seal is returned to said corresponding inlet.
 6. The fluid pump assembly of claim 5, wherein said scavenging groove is an annular groove surrounding said piston rod.
 7. The fluid pump assembly of claim 6, wherein said scavenging groove is located on a side of a corresponding said wiper seal opposite from said pressure loaded seal.
 8. The fluid pump assembly of claim 5, wherein said fluid cylinder is an air cylinder. 